Process for making enzyme-containing granules

ABSTRACT

A granular free-flowing, non-dusting, non-tacky, enzymecontaining detergent composition is made by (a) forming a fluidized bed of enzyme particles and a particulate hydratable builder salt; (b) contacting the fluidized particles with an aqueous liquid to form agglomerates of said enzyme and builder salt; (c) recovering the agglomerates from the bed; and (d) tumbling the agglomerates for a period of from 3 to about 30 minutes.

United States Patent 11 1 Milesi et al.

PROCESS FOR MAKING ENZYME- CONTAINING GRANULES Inventors: Domenico Milesi; Remigo Natali,

both of Rome, Italy Assignee: Colgate-Palmolive Company, New

York, NY. I

Filed: Sept. 24, 1970 Appl, No.: 75,270

Foreign Application Priority Data Sept. 24, 1969 Italy ..40261 A/69 u.s. c1. .252/135, 23/313, 252 39, 5 252/132, 252/539, 264/117, 252/010. 2,

Int. Cl ..C1ld 3/06, 01 1d 7/42, c1 1d 11/00 Field oiSearch...23/313; 264/117; 252/99, 132, 252/135, 1310. 12

6/1969 Roald et al ..252/1 35 7/1968 Armstrong et al ..264/1l7 X 1 1 Jan. 30, 1973 3,247,118 4/1966 Matthaei ..252/99 3,227,790 l/1966 Bretschneider et al... .....264/l17 3,207,824 9/1965 Wurster et al .2641] 17 3,043,652 7/1962 Schytil ..264/1l7 X 2,742,436 4/1956 Jenkins ..252/l61 2,456,437 12/1948 Miles ..252/368 FOREIGN PATENTS OR APPLICATIONS 510,555 3/1955 Canada ..252/S39 2,009,267 1/1970 France ..252/135 1,226,479 3/1971 Great Britain, .....252/135 1,214,234 1l/l970 Great Britain ..252/l35 Primary ExaminerLeon D. Rosdol Assistant ExaminerDennis L. Albrecht Att0meyHerbert S. Sylvester, Ronald S. Cornell, Murray M. Grill, Thomas .1. Corum, Norman Blumemkopf, Richard N. Miller and Robert L. Stone [57] ABSTRACT A granular free-flowing, non-dusting, non-tacky, enzyme-containing detergent composition is made by (a) forming a fluidized bed of enzyme particles and a particulate hydratable builder salt; (b) contacting the fluidized particles with an aqueous liquid to form agglomerates of said enzyme and builder salt; (c) recovering the agglomerates from the bed; and (d) tumbling the agglomerates for a period of from 3 to about 30 minutes.

9 Claims, No Drawings PROCESS FOR MAKING ENZYME-CONTAINING GRANULES This invention relates to a method of making a granular free-flowing,non-dusting, non-tacky, enzymecontaining composition having high enzyme activity.

Powderedenzyrlnes have been employed in presoak and washing detergent compositions because they are particularly effective against various common stains which are fixed fto textiles and laundry. In particular, proteolytic enzymes, which possess the ability to digest and degrade protein matter, are effective in removing protein stains such as blood, sweat, milk, cocoa, gravy and other sauces from textiles and laundry. This digestion or degradation of protein matter facilitates removal of dirt by the detergent. Amylases and lipases are also useful in detergent cleaning.

An enzyme-containing laundry product can be prepared by mechanically mixing enzyme powder, i.e., a material wherein the particle size of a major proportion of the particles is smaller than 149 microns (0.149 mm.), with a granular or powdered mixture of the remaining ingredients in the laundry composition. However, due to the differences in particle size and density of the enzyme material and the mixture of the remaining ingredients segregation tends to occur, resulting in a non-uniform product.

It has been suggested that enzyme materials be bound to various hydratable, detergent builder salts. This is generally accomplished by contacting the powdered enzyme material with a particulate anhydrous or partially-hydrated builder salt in a mechanically agitated, powder mixer while adding water in an amount insufficient to fully hydrate the builder salt, i.e., about 30 percent of complete or full hydration. The resultant product still exhibits a considerable amount of fines. Furthermore, the presence of hydratable salt which has been bound to an enzyme with water in an amount insufficient to substantially fully hydrate the salt results in a composition which when added in a finished detergent has afhigh degree of contact with materials which may reduce enzyme activity. For example, during the course of its shelf life, a finished detergent composition containing perborate bleach may be in contact with a moist atmosphere which reduces enzyme activity. 7

Accordingly, an object of the present invention is a process for preparing enzyme-containing laundry compositions wherein at least about 90 percent of the particles have a size in the range of 0.1 mm. to2.4 mm. and preferably in the range of 0.15 mm. to 2.0 mm. A further object of the described process is the preparation of an enzyme-containing granulate havinggood flowability and minimal caking tendencies which can be admixed with other granular detergent compositions to make an enzyme-containing washing product.

The inventive process for preparing a granular, en'- zyme-containing washing composition comprises the steps of (a) forming a fluidized bed comprising an upwardly flowing gas stream having turbulently suspended therein an enzyme preparation in particulateform and a carrier in particulate form, said carrier comprising a water-soluble, hydratable, builder salt; (b) contacting said particulate mixture with an aqueous liquid to wet the surfaces thereof, thereby forming agglomerates of enzyme preparation and carrier, the aqueous liquid being added in an amount at least suffrcient to substantially fully hydrate the builder salt; (c) maintaining the agglomerates in said fluidized bed until agglomerates are formed having a particle size and density sufficient to cause said agglomerates to move downwardly through said upwardly flowing gas stream under the force of gravity; and (d) passing a gas over the surface of a tumbling bed of agglomerates thereby removing up to 20 percent of the water added and conditioning said surfaces to a substantially non-caking state. i

'The described process produces enzyme-containing agglomerates or granules wherein a major proportion of the particles preferably pass through a 10 mesh screen (screen opening 2.0 mm.) and are retained on a 100 mesh screen (screen opening 0.149 mm.). Only a minor proportion of the particles have a particle size larger than 10 mesh, i.e., 0 5 percent by weight, or smaller than 100 mesh, i.e., 0 to 20 percent and preferably less than 10 percent by weight maximum. All screen sizes used herein are 'U.S. Standard. In addition, the agglomerates are substantially dust free, i.e., particles smaller than 10 microns are less than 50 ppm, preferably less than 10 ppm. by weight. (The amount of dust in the agglomerates is determined by subjecting 24 ounces of agglomerates to a free fall of 96 cm. in an enclosed chamber and quantitatively collecting on a slide the dust settling during a 30 second period beginning 10 seconds after the initiation of free fall.) Finally, the agglomerates are substantially free flowing and substantially free from lumping or caking during bulk storage.

The composition of the foregoing agglomerates is expressed on a solids or water-free basis because the amount of water therein varies with the amount and the identity of the inorganic salt component of the carrier. Generally, the agglomerates comprise from 2 to 50 percent by weight of enzyme preparation on a solids basis, i.e., 0.1 to 4 percent by weight of active enzyme, 20 to 98 percent by weight of hydratable builder salt on a solids or anhydrous basis, and water in an amount sufficient to substantially, completely hydrate the builder salt to produce a hydrate thereof containing about to 130 percent of the theoretical amount of water in the completely hydrated salt. Thus, the resultant agglomerate comprises enzyme preparation and a substantially completely hydrated builder salt. The enzyme preparation content of the agglomerates is preferably 5 to 20 percent by weight on a solids basis, with the optimum being about 10 percent by weight.

Such agglomerates may be used directly as a presoak product or may be blended with other spray-dried or'heat-dried detergent particles to form a heavy-duty washing product. The pre-soak products typically contain at least 10 percent by weightof enzyme preparation which corresponds to at least 15 Anson units per 100 grams of granules; whereas the heavy-duty washing products usually contain about 0.1 to 4 percent by weight of enzyme preparation. The amount of the enzyme-containing agglomerates present in the detergent composition will, of course, depend to some extent on the amount of the detergent composition which is to be added to the wash water. For detergent compositions which are intended for use at concentrations of about 0.15 percent in the wash water of an automatic home laundry machine, one suitable amount of granular enzyme product is such as to provide 1 Anson unit of the alkaline protease for each 100 to 500 (e.g., 200 to 400) grams of the detergent composition. Thus, in a heavy duty laundry detergent composition, the enzyme-containing granulate composition will form about 0.3 to about 30 percent by weight and the balance will be a mixture of water-soluble, synthetic organic detergent and water-soluble builder salts wherein the ratio of detergent to builder salts is in the range of 1:2 to 1:10 by weight.

Steps (a) (c) in the described process are generally carried out in a substantially cylindrical reaction vessel which is tapered conically toward the bottom and has openings at the top and the bottom. A suction fan draws gas through the discharge of agglomerates from the opening at the bottom of the vessel and creates an updraft within the vessel, which serves to suspend and agitate the particulate materials charged so as to form a fluidized bed. The gas stream eventually exits through a duct at the top of the vessel and passes through a separator and the suction fan before being exhausted to the atmosphere or being recycled to the gas stream entering the bottom of the vessel.

The particulate materials are introduced into the top of the reaction vessel through a supply pipe. Feed means deliver the material to the supply pipe from a feed hopper. Preferably the feed means proportion the material from a lock chamber located below a feed hopper into an entraining air stream from which it is removed in a cyclone separator and introduced into the reaction chamber through an axially located immersion tube. The entering particulate materials form an agitated or fluidized bed in the upwardly-flowing gas stream in the lower, conical section of the reaction vessel.

This agitated bed is contacted with an aqueous liquid introduced through at least one nozzle located on the periphery of the lower portion of the reaction vessel adjacent the fluidized-bed. Often additional nozzles are located in the opening at the bottom of the reaction vessel so that the descending particles fall downwardly against a conical spray of aqueous liquid. Preferably, the aqueous liquid is intro-duced through a two fluid nozzle supplied with aqueous liquid and compressed gas whereby the aqueous liquid is contacted with the particulate materials in the form of a mist or spray of discrete droplets. Upon contact of the particulate materials and the aqueous liquid the surfaces of the particles are modified to a state whereby agglomerates of the particulate material form. The resultant agglomerates of enzyme, hydratable salt, and aqueous liquid attain a particle size which is variable with the flow rate of the upwardly flowing gas stream, i.e., the particle size increases or decreases in substantially direct proportion to the flow rate of the gas stream. Thus, the agglomerates are held in suspension until the size and weight of the resultant agglomerates overcome the force of the updraft of gas and they fall out of the fluidized bed and, ultimately, the reaction vessel.

During the spraying operation the liquid and solid particles are in a continuous state of motion. Unwetted particles remain in suspension until they are either wetted, join with an existing agglomerate or are entrained in the exhaust gas stream. Agglomerates continuously fall out of the fluidized bed and are replaced with unsprayed, unwetted solid particles of enzyme and hydratable salt. Any untreated particles entrained in the gas stream are recovered from the exhaust gas stream and recycled to the feed stream of particulate solids. All of the agglomerates of enzyme, hydratable salt, and water are discharged from the reaction vessel through the substantially cylindrical opening at the bottom of the frustoconical section through which the agitating gas stream enters.

The agglomerates from the reaction vessel either fall directly or are conveyed by conduit to an apparatus where step (d), the conditioning step, is carried out. This conditioning step is preferably accomplished by tumbling in an inclined rotary drum for a period of 3 to about 30 minutes while circulating a gas therepast. Such tumbling treatment effectively achieves moisture equilibration in a number of ways. More specifically, as the agglomerates pass through the inclined, rotating drum, a continuous changing portion of the agglomerates is subjected to free fall in the circulating gas stream while the remainder of the agglomerates is maintained in a rolling bed which presents a continuously changing surface to the flowing gas stream. Both the free fall treatment and the rolling bed treatment of the agglomerates facilitate moisture equilibration within and between agglomerates. Disparities in moisture concentrations on the surface of any single agglomerate are minimized during free fall through the gas since the entire surface tends to reach the same moisture level due to Raoults law. Further, differences in the moisture concentration between various agglomerates tends to be minimized due to physical transfer of moisture between adjacent agglomerates in the rolling bed. Finally, the continuously changing surface of agglomerates in the rolling bed which is in contact with the flowing gas serves to diminish moisture differences between agglomerates by virtue of Raoults law.

The relative humidity of the circulating gas, e.g., air, generally increases between the time the gas enters and leaves the drum, and thus the water concentration in the agglomerates is reduced during the conditioning period. The proportion of water removed from the agglomerates is variable and depends upon the amount of material and its moisture content, average agglomerate size, average residence time in the drum, the gas flow rate, the gas temperature, the relative humidity of the gas, the speed of rotation of the drum, and the baffling in the drum. By properly controlling and integrating the foregoing variables, from about 2 to 20 percent by weight of the water added during the agglomeration step, i.e., about 0.4 to 4 .percent by weight of the agglomerate, will be removed during conditioning. The identity of the hydratable salt also affects the amount of water removed because the amount of free water present in the agglomerate varies with the rate of hydration of each salt.

Usually, the agglomerates are tumbled while flowing a stream of air through the rotating drum in a direction countercurrent to the flow of agglomerates through the drum. Alternatively, concurrent air flow may be used. The air velocity is generally in the range of 1.0 to 2.4 meters per second (m./sec.), preferably 1.5 to L8 m./sec., and the temperature of the air is in the range of 1 0 to +40C., preferably from 10 to 25C. The speed a bed depth in the range of 0.5 to 5.0 cm. The baffles,

i.e., flights are usually located on the inner surface of the drum, but where the diameter of the drum exceeds one meter, it may be desirable to add flights in the empty or middle portion of the drum.

The conditioning step also serves to reduce the fines content, i.e., the proportion of particles having a diameter of microns or less, because the small particles of enzyme preparation which may be present during tumbling can be agglomerated in the rolling bed with other larger enzyme preparation-containing agglomerates. Further, any enzyme preparation particles not firmly adhered to the surface of the agglomerate will be removed and may either be reagglomerated in the bed or entrained in the circulating gas stream during the period of free fall. Such entrained enzyme preparation may subsequently be removed from the gas in a cyclone separator or similar apparatus and recycled to the enzyme preparation storage bin or feed stream entering the agglomerating chamber.

The agglomerates discharged from the fluidized bed should be conditioned by treating said agglomerates under conditions which insure moisture equilibration. It is believed that it is necessary to equilibrate the moisture within andbetween agglomerates in order to render the surface thereof non-tacky. More specifically, similar equilibration is not obtained by aging in bulk, either in a bin or on a conveyor, because only a portion of the surface of the agglomerates in the top layer of agglomerates is in contact with the surrounding atmosphere and the agglomerates in the middle and bottom layers of the bed or bin are never in contact with the surrounding atmosphere. Also, because the conditioning occurs under essentially quiescent conditions, no physical contact ever occurs between granules in different layers in the same container.

in order to prepare the desired agglomerates, it is essential to control the proportions and flow rates of the essential ingredients comprising the agglomerate dur-' ing steps (a) (c) and to correlate same with the flow rate and distribution of both the agitating gas stream and the aqueous liquid used as the agglomerating fluid.

The flowrate and distribution of the agitating gas stream are important because the particle size and weight of the agglomerates varies directly therewith. Generally, the mass flow rate of the agitating gas can be varied to produce'an inlet gas velocity selected from the range of 0.30 m./sec. to 0.90 m./sec., preferably in the range of 0.45 m./sec. to 0.75 m./sec. As stated above, larger granules form at the higher gas velocities because the particles are maintained in the fluidized bed for a longer period of time before'they attain a sufficient weight to overcome the force of updraft of gas. The temperature of the agitating gas which is preferably air will generally range from about --l0C. to about +40C. and preferably will range from about -5C. to +l5C. Below about l0C. the discharged agglomerates have poor flow characteristics. On the other hand, at temperatures above about40C., the rate of hydration of phosphate is low.

The amount, distribution and composition of the aqueous liquid added are important process variables, also. As stated heretofore, the aqueous liquid preferably should be added in the form of a mist. The proportion of aqueous liquid added should be sufficient to substantially completely hydrate the hydratable salt portion of the carrier. More particularly, the amount of water added should be in the range of to 130 percent of the theoretical amount needed to result in the complete hydration of the hydratable salt, and that amount will vary according to the identity of the hydratable salt and the extent of its initial hydration.

In addition, the rate at which the aqueous liquid is added must be integrated with the rates of addition of the other ingredients and the flow rate of the agitating gas. If less than about 90 percent of the theoretical amount is added, the granulation is not complete and the resulting product will contain larger amounts than desired of particles smaller than 10 p.; whereas, if more than 130 percent of the theoretical weight is added, the resultant agglomerates are too wet causing flowability and caking problems. Moreover, the stability of the enzyme during aging is affected.

Generally, the aqueous liquid will be water alone. However, it is preferred to use an aqueous liquid comprising 5 to 40 percent by weight of a water-soluble nonionic surface active agent and 60 to percent by weight of water because it appears to cause more of the enzyme to be attached to an interior surface of the water-soluble hydratable builder salt. An increase in the interior attachment of the enzyme reduces the amount of enzyme in the granulate surface which can come in contact with components of heavy duty detergent compositions, e.g., alkaline silicates, peroxide bleach, etc., which adversely affect enzyme activity. Also, such interior attachment is believed to reduce the proportion of enzyme which is subject to surface abrasion, thereby reducing the amount of enzyme dust generated in transporting and packaging the resultant granulate during the manufacturing process or in admixing said granulate with other ingredients in the manufacture of other enzyme-containing detergent products. Further, it appears that the nonionic surface active agent introduces a degree of plasticity into the resulting granule so that the granule is less crystalline and, accordingly, less subject to breakage or abrasion with an attendant increase in dustiness.

When the aqueous liquid comprising nonionic detergent is used in the described process, the proportion of nonionic detergent in the agglomerates will vary from 1 to 25 percent by weight thereof on a solids basis. Preferably, the agglomerates will contain 2 to 20 percent by weight of nonionic detergent on a solids basis, and most preferably about 2.5 to 5 percent by weight on a solids basis.

'The water-soluble nonionic surface active agent which is dissolved in water and then granulated with the premix of enzyme and hydratable builder salt may be in the form of a liquid, paste or solid at room temperature. Such nonionicsynthetic organic detergents are generally the condensation product of an organic aliphatic or alkyl aromatic hydrophobic compound and .hydrophilic ethylene oxide groups or the polyhydration product thereof, i.e., polyethylene glycol. Practically any hydrophobic compound having a carboxy, hydroxy, amido, or amino group with a free hydrogen attached to the nitrogen can be condensed with ethylene oxide to form a nonionic detergent. Suitable nonionic detergents include the polyethylene oxide condensate of one mole of alkyl phenol containing from about six to about 12 carbon atoms in a straight or branched chain configuration with about to 30 moles of ethylene oxide, e.g., nonyl phenol condensed with 9 moles of ethylene oxide; the condensation product of a higher alcohol containing about eight to 22 carbon atoms in a straight or branched chain configuration with about 5 to 30 moles of ethylene oxide, e.g., lauryl-myristyl alcohol condensed with 16 moles of ethylene oxide; the condensation product of ethylene oxide on a hydrophobic base formed by the condensation of propylene oxide on propylene glycol wherein the molecular weight of the hydrophobe ranges from about 1,500 to 1,800 and the polyethylene oxide content may comprise up to 50 percent of the total weight of the condensate; and the ethylene oxide addends of monoesters of hexahydric alcohols and inner ethers thereof with higher fatty acids containing about 10 to 20 carbon atoms, e.g., sorbitan monolaurate, sorbitan monooleate, and mannitan monopalmitate.

Good results have also been obtained where watersoluble, anionic organic detergents or water-soluble organic polymers are substituted for the nonionic detergent component in the foregoing aqueous nonionic detergent solution. Suitable anionic detergents include alkyl sulfates, alkyl polyethenoxy (l-6 moles) sulfates, alkyl sulfonates, higher acyl monoglyceride sulfates or sulfonates, higher acyl taurides, alkenyl sulfonates, and alkyl aryl sulfonates, wherein the alkyl, alkenyl, or higher acyl group contains from eight to 18 carbon atoms. The particular anionic detergent will usually be present in the form of a salt which will be selected from the group of sodium, potassium, ammonium, substituted ammonium, and magnesium salts. The sodium and potassium salts are preferred. Suitable organic polymers include alkali metal carboxymethyl cellulose salts, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxypropyl methyl cellulose, and the like.

The enzymes suitable for use in the inventive process comprise proteolytic enzymes which are active upon protein matter and catalyze digestion or degradation of such matter when present as in linen or fabric stain in a hydrolysis reaction. Generally, the enzymes are effective in a pH range of about 4-1 2, and are effective even at moderately high use temperatures. They are also effective at ambient temperature and temperatures above about 10C. Particular examples of proteolytic enzymes which may be used in the instant invention include pepsin, trypsin, chymotrypsin, papain, bromelin, colleginase, keratinase, carboxylase, amino peptidase, elastase, subtilisin and aspergillopepidase A and B. Preferred enzymes are subtilisin enzymes manufactured and cultured from special strains of spore forming bacteria, particularly Bacillus subtilis.

Proteolytic enzymes such as Alcalase, Maxatase, Protease AP, Protease ATP 40, Protease ATP 120, Protease 11-252, Protease ATP 360, Alkaline Protease No. l, Proteinase GV, Protease 2200C., Protease A 300, Bioprase AL 15 and Protease L-423 are among those enzymes derived from strains of spore forming bacillus, such as Bacillus subtilis.

Different proteolytic enzymes have different degrees of effectiveness in aiding in the removal of stains from textiles and linen. Particularly preferred as stain removing enzymes are subtilisin enzymes.

Metalloproteases which contain divalent ions such as calcium, magnesium or zinc bound to their protein chains are also of interest.

The enzyme preparations are generally extremely fine powders. In a typical powdered enzyme preparation, the particle diameter generally ranges from 0.001 mm. to 0.40 mm., and as much as percent of the material may pass through a 100 mesh (U.S. Standard) sieve. In the enzyme preparations inorganic salts, e.g., alkali metal and alkaline earth metal salts are generally used as the diluent. Typically the enzyme comprises from 1 to percent by weight of the enzyme preparation. For example, a typical Alcalase enzyme material analyzes (by weight) 6.5% enzyme, 4% water, 70% sodium chloride, 15.5% sodium sulfate, 3.5% calcium sulfate, and 0.5% organic impurities. Chemically they are typically stable in the pH range of 5 to 10, particularly at an alkaline pH of 8.0 to 9. Generally, they are effective against various types of soil in an aqueous medium having a temperature of about 20C. to about 802 C. Naturally, different proteolytic enzymes have different degrees of effectiveness in aiding in the removal of specific stains from textiles and linen.

Instead of, or in addition to, the proteolytic enzyme, an amylase may be present such as a bacterial amylase of the alpha type (e.g., obtained by fermentation of Bacillus subtilis). One very suitable enzyme mixture contains both a bacterial amylase of the alpha type and an alkaline protease, preferably in proportions to supply about 100,000 to 400,000 Novo alpha-amylase units per Anson unit of said alkaline protease.

Generally, the carrier used in the process of this invention will comprise a major proportion of water-soluble, hydratable builder salt. Usually, the water-soluble, hydratable builder salts used in the process of this invention provide a pH in the range of4 to 12, preferably in the range of 7 to 11. The water-soluble hydratable builder salt component may be asingle salt, a mixture of hydratable salts, a mixture of a hydratable salt with non-hydratable, water-soluble builder salts, or a portion of a multi-component detergent granule.

The particles of hydratable builder salt which are mixed with the powdered enzyme generally range in particle size from about 0.044 mm. to about 3.36 mm, i.e., corresponds to a U.S. Sieve range of 6 mesh to +325 mesh. Since the typical spray dried detergent products range from about 0.2 mm. to 2.0 mm. in particle size, salts having a particle size within the foregoing range may be prone to dusting. Therefore, the preferred size range of the hydratable builder salt is 0.2 mm. to 2.0 mm., with a preferred density range of 0.2 to 1.0 grams/cc.

Typical examples of usable hydratable organic builder salts which may be employed alone or in the aforementioned admixtures include the trisodium salt of nitrilotriacetic acid and the di-, tri-, and tetrasodium salts of ethylene-diamine tetra-acetic acid. Preferred inorganic hydratable builder salts are the alkali metal polyphosphate salts which have the property of inhibiting precipitation of calcium and magnesium material in aqueous solution and of contributing to the heavy-duty nonionic agent.

performance of the detergent product. They may be considered as derived from orthophosphoric acid or the like by the removal of molecularly bound water, though any suitable means of manufacture may be employed if desired. Such complex or molecularly dehydrated polyphospahte salts may be 'used in the form of the normal or completely neutralized salt, e.g., pentapotassium tripolyphosphate, pentasodium tripolyphosphate, or in acid form, e.g., potassium acid tripolyphosphate. The alkali metal salts of tetraphosphoric acid may be used also. The alkali metal polyphosphate salts may be used in either anhydrous form or partially hydrated form.

Other hydratable alkaline builder salts may be employed also, such as the soluble alkali metal borates, sulfates, carbonates, and silicates. Usually, the silicates will be employed in suitable combination with other hydratable builder salts such as the polyphosphates. Suitable silicates are those available in solid form and having an alkali oxide to silicon dioxide ratio within the range of about 1.2.35 to 1:4, and preferably from about 1:2.5 to 1:3.Examples are sodium silicates having an Na O to SiO ratio of 122.35, 12.5, and 132. More a1- kaline silicates adversely affect the stability of the enzyme. The sodium and potassium'hydratable builder salts are preferred, and the most highly preferred builder salt is anhydrous sodium tripolyphosphate.

The granulate composition is expressed on a solids basis because the amount of water present varies with the identity and the amount of each particular hydratable salt. For example, 0.294 parts by weight of water are required for each part of anhydrous. sodium tripolyphosphate if the stable sodium tripolyphosphate hexahydrate is formed, whereas, 1.26 parts by weight of water are required for each part of sodium sulfate if the stable sodium sulfate decahydrate is formed. For this reason the granulate composition comprising enzyme preparation attached to a substantially completely hydrated hydratable salt is specified as containing (a) 2 to50 percent by weight of enzyme preparation on a solids basis, (b) to 98 percent of a hydratable salt, i.e., anhydrous or partially hydrated hydratable salt, on a solids basis, and (c) water in an amount sufficient to substantially completely hydrate said hydratable salt to produce a hydrate thereof containing about 90 percent to about 130 percent of the theoretical amount of water in the completely hydrated salt. To the extent that the amount of water exceeds the water in the fully hydrated salt, the water will be free water. From the foregoing it is apparent that, in the absence of other ingredients, the composition of the granulate on a solids basis is identical to the composition of the'mixture of enzyme preparation, hydratable salt, and, optionally,

in order to further illustrate the nature of the described process and the manner of practicing same, the following examples are presented. All percentages and proportions in these examples, this specification and the appended claims are by weight unless otherwise indicated.-

EXAMPLE 1 2.5 parts of the condensation product of one mole of nonyl phenol and 9 moles of ethylene oxide are dissolved in 19.85 parts of water withv agitation at a temperature of 20C. The resultant solution containing 12.6 percent by weight of nonionic detergent exhibits a low viscosity at 20C., the temperature at which it is stored.

A powdered premix containing 12.8 percent by weight of enzyme preparation and 87.2 percent by weight of anhydrous penta-sodium tripolyphosphate is prepared by admixing 10 parts of proteolytic subtilisin enzyme Alcalasev and 67.65 parts of anhydrous pentasodium tripolyphosphate in an air mixer. The density of the particulate premix is 0.69 gm./cc. The proteolytic subtilisin enzyme preparation used has its maximum proteolytic activity at a pH of 8 9. This activity as measured at pH 7.5 on the commercial enzyme preparation available from Novo lndustri A/B, Copenhagen, Denmark is about 1.5 Anson Units per gram of the enzyme. The commercial enzyme preparation is a raw extract of Bacillus subtilis culture and contains about 6 percent of pure crystallized proteolytic material. The preparation is an extremely fine powder.

The particle size of the enzyme preparation and the anhydrous tripolyphosphate is shown by the following screen analyses:

Remaining on Mesh Mesh Opening (mm.) Enzyme Phosphate a pressure of 6 kg./cm The aqueous liquid is added at a rate sufficient to completely hydrate the anhydrous pentasodium tripolyphosphate to form the sodium tripolyphosphate hexahydrate.

The density of the agglomerated product discharging from the mixer is about 0.62 gm./cc. at the discharge temperature of 30C. The agglomerated product analyzes 21.7 percent moisture by weight (corresponds to 112 percent of the water required for complete hydration of the phosphate) and on that basis the agglomerates contain 3.1 percent nonionic detergent, 9.7 percent enzyme preparation and 65.5 percent sodium tri-polyphosphate (anhydrous basis). The product particle size is shown below:

0.04% by weight The foregoing product exhibits a low dust level when treated by the aforementioned dust test and has a satisfactory particle size. However, this product appeared to have caking tendencies based on a tackiness value of 1.45. The caking tendencies are determined by measuring the pressure, in kilograms, required to crush a cylindrical briquet of agglomerates formed under pressure of 10 kilograms in a mold having a diameter of 8 cm.

The foregoing product is fed into a drum having a diameter of 0.49 rn. and a length of 3.0 rn. at a rate of 120 kg./hr. The drum contains six equispaced baffles running lengthwise of the drum and is rotated at 8 revolutions per minute. The drum is inclined at an angle of 145 from the horizontal and the average residence time of the agglomerates therein is about minutes. Air at a temperature of 18C. is passed through the drum at a rate of 4.7 kg./min. in a direction countercurrent to the flow of product. In passing through the drum, the temperature of the agglomerates is reduced from 21C. to 18C. and the moisture content of the agglomerates is reduced from 21.7 to 18.0 percent by weight. Thus, approximately 17 percent of the water added during the agglomeration step is removed during the conditioning step.

The tackiness value of the conditioned granules is 0.85 in the caking test and represents a reduction of 41 percent as compared with the tackiness value of the agglomerates prior to conditioning. When the conditioned granules are stored in bulk, only slight caking is observed since some fragile, easily broken lumps are formed. In the absence of the conditioning step, severe caking problems are noted when the product is stored in bulk.

EXAMPLE 2 2.50 parts of the condensation product of one mole of nonylphenol and 9 moles of ethylene oxide are dissolved in 19.85 parts of water under agitation at a temperature of 18C. The resultant solution containing 12.6 percent by weight of nonionic detergent exhibits a low viscosity at 18C., the temperature at which it is stored.

A powdered premix containing 12.8 percent by weight of enzyme preparation and 87.2 percent by weight of anhydrous pentasodium tripolyphosphate is prepared by mixing 10 parts of proteolytic subtilisin enzyme Alcalase and 67.65 parts of anhydrous pentasodium tripolyphospahte in an air mixer. The density of the particulate premix is 0.69 gm./cc.

The proteolytic subtilisin enzyme preparation used has its maximum proteolytic activity at a pH of 8 9. This activity as measured at pH 7.5 on the commercial enzyme preparation available from Novo lndustri A/B, Copenhagen, Denmark is about 1.5 Anson Units per gram of the enzyme. The commercial enzyme preparation is a raw extract of bacillus subtilis culture and material. The preparation is an extremely fine powder.

The particle size of the enzyme preparation and the anhydrous tripolyphosphate is shown by the following screen analyses:

The aqueous nonionic solution is sprayed onto the fluidized bed of powdered premix maintained in a flowing stream of air having a temperature of 5C. and a velocity of 0.63 meters/second. The powdered premix and the aqueous nonionic solution are continuously dosed into the spray mixing chamber at approximate flow rates corresponding to 1560 kg./hr. and 440 kg./hr., respectively.

The solution of nonionic detergent is sprayed onto the fluidized bed of the particulate mixture of enzyme preparation and tripolyphosphate through 12 nozzles having an orifice size of 1.2 mm. at a pressure of 6 kg./cm. The aqueous liquid is added at a rate sufficient to completely hydrate the anhydrous pentasodium tripolyphosphate to form the sodium tripolyphosphate hexahydrate.

The density of the agglomerated product discharging from the mixer is about 0.60 gm./cc. at the discharge temperature of 30C. The agglomerated product analyzes 22.3 percent moisture by weight (corresponds to 114 percent of water required for complete hydration of the phosphate) and on that basis the agglomerates contain 2.6 percent nonionic detergent, 10.1 percent enzyme preparation and 66.5 percent sodium tripolyphosphate (anhydrous basis).

The product particle size is shown below:

The foregoing product exhibits a low dust level when tested by the aforementioned dust test and has a satisfactory particle size.

However, this product appeared to have caking tendencies based on a tackiness value of 1.65.

The foregoing product is fed into a drum having a diameter of 0.76 m. and a length of 3.6 m. at a rate of 650 kg./hr. The drum contains six equispaced baffles running lengthwise along the drum and is rotated at 6 revolutions per minute.

The drum is inclined at an angle of 115 from the horizontal and the average residence time of the agglomerates therein is about 9 minutes. Air at a temperature of 16C. is passed through the drum at a rate of 95 kg./min. in a direction countercurrent to the flow of product. In passing through the drum, the temperature of the agglomerates is reduced from 17 to C. and the moisture content of ,the agglomerates is reduced from 22.3 to 18.7 percent by weight. Thus, approximately 16 percent of the water added during the agglomeration step is removed during the conditioning step. 1;.1. -2

The tackiness value of the conditioned granules is 0.95 in the caking test and represents a reduction of 42 percent as compared with the tackiness value of the agglomerates prior to conditioning. When the conditioned granules are stored in bulk, only slight caking is observed since some fragile, easily broken, lumps are formed. ln the absence of the conditioning step, severe caking problems are noted when the product is stored in bulk.

What is claimed is:

1. An improved process for preparing a granular, enzyme-containing laundry composition consisting essentially of 2 to 50 percent by weight of enzyme preparation solids, to 98 percent by weight of anhydrous hydratable builder salt, and water, at least about 90 percent of the particles of said composition having a size in the range of 0.1 mm. to 2.4 mm., which comprises: (a) forming a fluidized bed comprising an up wardly flowing gas stream with a temperature of from l0C. to 40C. having'turbulently suspended therein a particulate enzyme preparation containing an enzyme selected from the group consisting of protease, amylase, and lipase, and having a particle diameter in the range of 0.001 mm. to 0.40 mm., and a particulate carrier having a particle size from about 0.44 mm. to about 3.36 mm., said carrier comprising a major proportion of a water-soluble, hydratable, builder salt; (b) contacting said mixture with an aqueous liquid to wet the surfaces thereof, thereby forming agglomerates of said enzyme and said carrier, said aqueous liquid being added in an amount sufficient to provide 90 to 130 percent by weight of the theoretical amount of water in said completely hydrated builder set; (c) maintaining said agglomerates in said fluidized bed until agglomerates are formed having a particle size and density sufficient to cause same to move downwardly through said upwardly flowing gas stream under the force of gravity; and (d) tumbling the agglomerates for a period of from three to about thirty minutes while circulating air having a temperature in the range of l0 to 40C. therepast, thereby removing up to 20% of the water added and conditioning the surfaces thereof to a substantially non-caking state.

2. A process as claimed in claim 1 wherein said enzyme and said carrier are premixed prior to being introduced into the fluidized bed.

3. A process as claimed in claim 1 wherein said flowing gas is air having a temperature of from 1 0 to +40 4. A process as claimed in claim 3 wherein the velocity of said air is from 1.0 meters per second to 2.4 meters per second. 1 g

5. A process as claimed in claim 1 wherein the exit gas from said fluidized bed is recycled tosaid flowing,

agitating gas stream.

6. A process as claimed in claim 1 wherein said aqueous liquid is selected from the group consisting of water, aqueous anionic and nonionic organic surface active agent solutions containing from i to 25 percent of said agent, and aqueous organic polymer solutions containing from 1 to 25 percent by weight of a polymer selected from the group consisting of carboxymethyl cellulose salts, polyvinyl alcohol, polyvinyl pyrrolidone, and hydroxypropyl methyl cellulose.

7. A process as claimed in claim 1 wherein said carrier is an anhydrous, alkali metal, polyphosphate salt.

8. A process as claimed in claim 7 wherein said polyphosphate salt is sodium tripolyphosphate.

9. The granular enzyme'containing composition made according to the process of claim 1. 

1. An improved process for preparing a granuLar, enzyme-containing laundry composition consisting essentially of 2 to 50 percent by weight of enzyme preparation solids, 20 to 98 percent by weight of anhydrous hydratable builder salt, and water, at least about 90 percent of the particles of said composition having a size in the range of 0.1 mm. to 2.4 mm., which comprises: (a) forming a fluidized bed comprising an upwardly flowing gas stream with a temperature of from -10*C. to 40*C. having turbulently suspended therein a particulate enzyme preparation containing an enzyme selected from the group consisting of protease, amylase, and lipase, and having a particle diameter in the range of 0.001 mm. to 0.40 mm., and a particulate carrier having a particle size from about 0.44 mm. to about 3.36 mm., said carrier comprising a major proportion of a water-soluble, hydratable, builder salt; (b) contacting said mixture with an aqueous liquid to wet the surfaces thereof, thereby forming agglomerates of said enzyme and said carrier, said aqueous liquid being added in an amount sufficient to provide 90 to 130 percent by weight of the theoretical amount of water in said completely hydrated builder set; (c) maintaining said agglomerates in said fluidized bed until agglomerates are formed having a particle size and density sufficient to cause same to move downwardly through said upwardly flowing gas stream under the force of gravity; and (d) tumbling the agglomerates for a period of from three to about thirty minutes while circulating air having a temperature in the range of -10* to 40*C. therepast, thereby removing up to 20% of the water added and conditioning the surfaces thereof to a substantially non-caking state.
 2. A process as claimed in claim 1 wherein said enzyme and said carrier are premixed prior to being introduced into the fluidized bed.
 3. A process as claimed in claim 1 wherein said flowing gas is air having a temperature of from -10* to +40*C.
 4. A process as claimed in claim 3 wherein the velocity of said air is from 1.0 meters per second to 2.4 meters per second.
 5. A process as claimed in claim 1 wherein the exit gas from said fluidized bed is recycled to said flowing, agitating gas stream.
 6. A process as claimed in claim 1 wherein said aqueous liquid is selected from the group consisting of water, aqueous anionic and nonionic organic surface active agent solutions containing from 1 to 25 percent of said agent, and aqueous organic polymer solutions containing from 1 to 25 percent by weight of a polymer selected from the group consisting of carboxymethyl cellulose salts, polyvinyl alcohol, polyvinyl pyrrolidone, and hydroxypropyl methyl cellulose.
 7. A process as claimed in claim 1 wherein said carrier is an anhydrous, alkali metal, polyphosphate salt.
 8. A process as claimed in claim 7 wherein said polyphosphate salt is sodium tripolyphosphate. 